Association of intravenous digoxin use in acute heart failure with rapid atrial fibrillation and short-term mortality according to patient age, renal function, and serum potassium

Background: Intravenous digoxin is still used in emergency departments (EDs) to treat patients with acute heart failure (AHF), especially in those with rapid atrial fibrillation. Nonetheless, many emergency physicians are reluctant to use intravenous digoxin in patients with advanced age, impaired renal function, and potassium disturbances due to its potential capacity to increase adverse outcomes.

Objective: We investigated whether intravenous digoxin used to treat rapid atrial fibrillation in patients with AHF may influence mortality in patients with specific age, estimated glomerular filtration rate (eGFR), and serum potassium classes.

Design: A secondary analysis of patients included in in the Spanish EAHFE cohort, which includes patients diagnosed with AHF in the ED.

Setting: 45 Spanish EDs.

Participants: Two thousand one hundred ninety-four patients with AHF and rapid atrial fibrillation (heart rate ≥100 bpm) not receiving digoxin at home, divided according to whether they were or were not treated with intravenous digoxin in the ED.

Outcome: The relationships between age, eGFR, and potassium with 30-day mortality were investigated using restricted cubic spline (RCS) models adjusted for relevant patient and episode variables. The impact of digoxin use on such relationships was assessed by checking interaction.

Main results: The median age of the patients was 82 years [interquartile range (IQR) = 76-87], 61.4% were women, 65.2% had previous episodes of atrial fibrillation, and the median heart rate at ED arrival was 120 bpm (IQR = 109-135). Digoxin and no digoxin groups were formed by 864 (39.4%) and 1330 (60.6%) patients, respectively. There were 191 deaths within the 30-day follow-up period (8.9%), with no differences between patients receiving or not receiving digoxin (8.5 vs. 9.1%, P = 0.636). Although analysis of RCS curves showed that death was associated with advanced age, worse renal function, and hypo- and hyperkalemia, use of intravenous digoxin did not interact with any of these relationships ( P = 0.156 for age, P = 0.156 for eGFR; P = 0.429 for potassium).

Conclusion: The use of intravenous digoxin in the ED was not associated with significant changes in 30-day mortality, which was confirmed irrespective of patient age or the existence of renal dysfunction or serum potassium disturbances.